Propuesta metodológica para la identificación de tierras marginales mediante productos derivados de teledetección y datos auxiliares

[EN] The concept of marginal land (ML) is dynamic and depends on various factors related to the environment, climate, scale, culture, and economic sector. The current methods for identifying ML are diverse, they employ multiple parameters and variables derived from land use and land cover, and mostly reflect specific management purposes. A methodological approach for the identification of marginal lands using remote sensing and ancillary data products and validated on samples from four European countries (i.e., Germany, Spain, Greece, and Poland) is presented in this paper. The methodology proposed combines land use and land cover data sets as excluding indicators (forest, croplands, protected areas, impervious areas, land-use change, water bodies, and permanent snow areas) and environmental constraints information as marginality indicators: (i) physical soil properties, in terms of slope gradient, erosion, soil depth, soil texture, percentage of coarse soil texture fragments, etc.; (ii) climatic factors e.g. aridity index; (iii) chemical soil properties, including soil pH, cation exchange capacity, contaminants, and toxicity, among others. This provides a common vision of marginality that integrates a multidisciplinary approach. To determine the ML, we first analyzed the excluding indicators used to delimit the areas with defined land use. Then, thresholds were determined for each marginality indicator through which the land productivity progressively decreases. Finally, the marginality indicator layers were combined in Google Earth Engine. The result was categorized into 3 levels of productivity of ML: high productivity, low productivity, and potentially unsuitable land. The results obtained indicate that the percentage of marginal land per country is 11.64% in Germany, 19.96% in Spain, 18.76% in Greece, and 7.18% in Poland. The overall accuracies obtained per country were 60.61% for Germany, 88.87% for Spain, 71.52% for Greece, and 90.97% for Poland.[ES] El concepto de tierra marginal (ML) es dinámico y depende de factores relacionados con el entorno, el clima, la escala, la cultura y la economía. los métodos actuales de identificación de ML son también diversos y están basados en múltiples parámetros y variables derivados del uso y cobertura del suelo reflejando, en su mayoría, fines de gestión específicos. En este artículo se presenta una propuesta metodológica para la identificación de tierras marginales mediante el uso de productos derivados de teledetección y datos auxiliares, validándose sobre muestras obtenidas en cuatro países europeos: Alemania, España, Grecia y Polonia. La metodología combina datos de usos y coberturas del suelo como indicadores excluyentes (bosque, tierras de cultivo, áreas protegidas, áreas impermeables, cambios de usos del suelo, cuerpos de agua y áreas de nieve permanente) e información ambiental como indicadores de marginalidad, esto es, (i) propiedades físicas del suelo como la pendiente, profundidad de suelo, erosión del suelo, textura, porcentaje de fragmentos de textura gruesa del suelo, etc.; (ii) factores climáticos como el índice de aridez; (iii) propiedades químicas del suelo como pH, capacidad de intercambio catiónico, contaminantes y toxicidad, entre otros, con el objetivo de abordar una visión común de la marginalidad que integre un enfoque multidisciplinar. Para obtener las coberturas de ML primero se analizaron los indicadores excluyentes para delimitar las áreas con un uso del suelo establecido. En segundo lugar, se determinaron los umbrales para cada indicador de marginalidad a través de los cuales el suelo se transforma, disminuyendo progresivamente su aprovechamiento productivo. Finalmente, la superposición de las capas de indicadores de marginalidad se llevó a cabo con la herramienta Google Earth Engine. El resultado final se categorizó en 3 niveles de ML con diferente productividad: alta, baja y tierras potencialmente inadecuadas. Los resultados obtenidos indican que el porcentaje de tierras marginales sobre la extensión total de cada país analizado es de 11,64% en Alemania, 19,96% en España, 18,76% en Grecia y 7,18% en Polonia. La precisión global obtenida por país fue del 60,61% para Alemania, del 88,87% para España, del 71,52% para Grecia y del 90,97% para Polonia.This research has been funded by the European Commission through the H2020-MSCA-RISE-2018 MAIL project (grant 823805) and by the Fondo de Garantía Juvenil en I+D+i from the Spanish Ministry of Labour and Social Economy.Torralba, J.; Ruiz, L.; Georgiadis, C.; Patias, P.; Gómez-Conejo, R.; Verde, N.; Tassapoulou, M.... (2021). Methodological proposal for the identification of marginal lands with remote sensing-derived products and ancillary data. En Proceedings 3rd Congress in Geomatics Engineering. Editorial Universitat Politècnica de València. 248-257. https://doi.org/10.4995/CiGeo2021.2021.12729OCS24825

Validation dataset for Land Cover Map of Europe 2017

Thematic accuracy assessment of land cover/use products requires reliable reference data that enable their qualitative and quantitative evaluation. Such dataset with up-to-date information on a predefined class composition and spatial distribution is rarely available and its preparation requires an appropriate methodological approach adjusted to a specific product. Development of a new pan-European land cover/use map, generated from Copernicus Sentinel-2 data 2017 within the Sentinel-2 Global Land Cover (S2GLC) project carried out under a programme of and funded by the European Space Agency, provided an opportunity to design and develop an unique dataset dedicated to validation of this product. The dataset was prepared by twofold stratified random sampling. The first selection designated validation sites represented by Sentinel-2 image tiles and was performed on a country level with county borders used as a stratum. In the second selection validation samples were chosen randomly within the validation sites with stratification based on classes of the CORINE Land Cover database. The final dataset composed of samples visually checked by experienced image interpreters consists of a total number of 52,024 samples spread over the European countries. The samples represent 13 land cover/use classes including artificial surfaces, natural material surfaces (consolidated and un-consolidated), broadleaf tree cover, coniferous tree cover, herbaceous vegetation, moors and heathland, sclerophyllous vegetation, cultivated areas, vineyards, marshes, peatbogs, water bodies and permanent snow cover. Each sample provides information about the occurrence of one of the predefined land cover or land use classes within an area of 100 m² represented by a single pixel (10 m size) of Sentinel-2 imagery for the year 2017. The described dataset was used for the accuracy assessment process of the product Land Cover Map of Europe 2017 resulting from the S2GLC project and provided an estimate of the overall accuracy at the level of 86.1%

Integrating Data-Driven and Participatory Modeling to Simulate Future Urban Growth Scenarios: Findings from Monastir, Tunisia

Current rapid urbanization trends in developing countries present considerable challenges to local governments, potentially hindering efforts towards sustainable urban development. To effectively anticipate the challenges posed by urbanization, participatory modeling techniques can help to stimulate future-oriented decision-making by exploring alternative development scenarios. With the example of the coastal city of Monastir, we present the results of an integrated urban growth analysis that combines the SLEUTH (slope, land use, exclusion, urban extent, transportation, and hill shade) cellular automata model with qualitative inputs from relevant local stakeholders to simulate urban growth until 2030. While historical time-series of Landsat data fed a business-as-usual prediction, the quantification of narrative storylines derived from participatory scenario workshops enabled the creation of four additional urban growth scenarios. Results show that the growth of the city will occur at different rates under all scenarios. Both the “business-as-usual” (BaU) prediction and the four scenarios revealed that urban expansion is expected to further encroach on agricultural land by 2030. The various scenarios suggest that Monastir will expand between 127–149 hectares. The information provided here goes beyond simply projecting past trends, giving decision-makers the necessary support for both understanding possible future urban expansion pathways and proactively managing the future growth of the city